Journal of

Dental Research, Dental Clinics, Dental Prospects

Original Article

Sexual Dimorphism in Human Mandibular Canines: A

Radiomorphometric Study in South Indian Population Rishabh Kapila 1* • K.S. Nagesh 2 • Asha R. Iyengar 3 • Sushma Mehkri 4

1Senior Lecturer, Department of Oral Medicine and Radiology, Guru Nanak Dev Dental College and Research Institute, Sunam, Punjab, India 2Principal and Head of Department of Oral Medicine and Radiology, DAPM R.V. Dental College and Hospital, Bangalore, India 3Professor, Department of Oral Medicine and Radiology, DAPM R.V. Dental College and Hospital, Bangalore, India 4Lecturer, Department of Oral Medicine and Radiology, DAPM R.V. Dental College and Hospital, Bangalore, India *Corresponding Author; E-mail: rishabh_kapila@rediffmail.com

Received: 26 January 2011; Accepted: 8 May 2011 J Dent Res Dent Clin Dent Prospects 2011; 5(2):51-54 This article is available from: http://dentistry.tbzmed.ac.ir/joddd

© 2011 The Authors; Tabriz University of Medical Sciences This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract Background and aims. The aim of this study was to determine whether variations in the mesiodistal dimensions of

mandibular canines had any role in sex determination. Materials and methods. The study comprised of patients in the 19‒24-year age group (20 males and 20 females). Me-

siodistal dimensions of mandibular canines was measured at the maximum mesiodistal width, first intraorally, then on plas-

ter models of the same patient, followed by intraoral periapical radiograph of the same patient. The values were subjected to

statistical analysis using t-test. Results. It might be concluded from the results that there exists a definite statistically significant difference in the mesio-

distal width of mandibular canines when measured for males and females. Moreover, the left mandibular canine showed a

greater sexual dimorphism (9.7%) when compared to the right mandibular canine (7.4%).

Conclusion. The present study establishes a statistically significant sexual dimorphism in mandibular canines. It can be

concluded that the standard mandibular canine index is a quick and easy method for determining sex and in identification of

an unknown individual.

Key words: Mandibular canine width, radiomorphometric study, sexual dimorphism.

Introduction

uman teeth are the hardest and chemically the most stable tissues in the body, and are ex-

tremely durable even at high temperatures. Teeth can be identified even when the rest of the body has un-dergone decomposition. They are therefore invalu-able for identification on fragmentary adult skeleton.

Teeth are readily accessible for examination and since no two teeth have similar morphology, they form an excellent forensic tool for sex determination. The identification of sex is of significance in case of major disasters where bodies are often damaged be-yond recognition. Of all the teeth in the human denti-tion, canines are the least frequently extracted teeth (possibly because of the relatively decreased inci-

H

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52 Kapila et al.

dence of caries and periodontal disease).1 Mandibu-lar canines are considered to be the key teeth for sexual dimorphism.2 Also, canines are reported to withstand extreme conditions and have been recov-ered from human remains even in air disasters and hurricanes.1

 Figure 1. Measurement of mesiodistal width of man-dibular canine by clinical examination. 

Tooth size standards based on odontometric inves-tigations can be used in age and sex determination as human teeth exhibit sexual dimorphism.3 Males pos-sess larger tooth crowns than females in contempo-rary human populations. This may be due to a longer period of amelogenesis for both deciduous and per-manent dentitions in males.4

Few studies have established that the mesiodistal diameter of lower canine is less in females than males and they have established variations. Hence, the present study aimed to measure the mesiodistal diameter of both mandibular canines so as to estab-lish canine measurement variations in sex determina-tion.

 

 Figure 2. Measurement of mesiodistal width of man-dibular canine on plaster models. 

Materials and Methods

The study comprised of 40 subjects in the 19‒24-year age group, of which 20 were males and 20 fe-males.

The significant exclusion criteria for selection of the study sample were the presence of partially erupted/ectopically erupted teeth, patients with den-tal/occlusal abnormalities (such as rotation, crowd-ing, occlusal disharmony etc), teeth showing physi-ologic or pathologic wear and tear (e.g. attrition, abrasion, abfraction, erosion), and patients with dele-terious oral habits (like bruxism).  

Mesiodistal diameter of mandibular canines was measured at the maximum mesiodistal width, first intraorally, then on plaster models of the same pa-tient, followed by measurement on tracings of in-traoral periapical radiographs (made by paralleling technique for standardization) of the same patient (Figures 1, 2 and 3) (Table 1).

The protocol was reviewed by the institutional eth-ics committee and the project was undertaken after a signed detailed consent form by the patients.

It was followed by calculation of sexual dimor-phism according to the formula given by Garn and

Lewis:5 100×f

m

XX

Xm = Mean value of canine width in males Xf = Mean value of canine width in females

Data was subjected to statistical analysis using ANOVA.

Figure 3. Measurement of mesiodistal width of man-dibular canine on tracings of intraoral periapical ra-diograph.

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Sexual Dimorphism in Mandibular Canines 53

Table 1. Mean mesiodistal width of mandibular canine obtained by clinical examination, plaster models and by ra-diographic examination.

Statistical Analysis

The mean values of the mesiodistal width of left and the right mandibular canines in males and females were obtained by clinical examination, measurement on plaster models and radiographic examination and analyzed (Table 1).

The mean value of the mandibular canine width in males and females on the right and left sides were compared using t-test. Moreover, the right and left sides were compared using independent t-test, irre-spective of the gender.

The Excel and SPSS (SPSS Inc, Chicago) software packages were used for data entry and analysis.

Results

From the results of the present study, it is evident that the mesiodistal width of mandibular canines as determined by clinical examination, measurement on plaster models and radiographic examination was statistically insignificant (P > 0.05).

The mean values of mandibular canine widths in males and females on the right and left sides were compared using t-test and were found to be statisti-cally significant (P < 0.0001). The mean value was greater in males as compared to females and left ca-nine was bigger in size than the right irrespective of gender. This was irrespective of whether measure-ments were made by clinical examination, measure-ment on plaster models or by radiographic examina-tion.

The present study also indicates the probability of sex determination to an extent as high as 90% (when the width of either canine was greater than 7 mm, the sex was male). Moreover, the left mandibular canine showed a greater sexual dimorphism (9.7%) when compared to the right mandibular canine (7.4%) (Figure 4).

Discussion

Mandibular canines are believed to demonstrate the greatest percentage of sexual dimorphism in their mesiodistal width amongst all the teeth.5-8

Hashim HA and Murshid ZA in their study on 720 teeth on pretreatment orthodontic casts in a Saudi population aged 13‒20 years noticed that the ca-nines were the only teeth to exhibit dimorphism.9 In a continuation of the same study, they also deter-mined that there was no statistically significant dif-ference between the left and right canines, suggest-ing that measurement of teeth on one side could be truly representative when the corresponding meas-urement on the other side was unobtainable.10 In another study on Saudi Arabian sample of 503 schoolchildren by Al-Rifaiy et al it was reported that the mean values for left and right maxillary and mandibular canine mesiodistal width was less for females than for males, with no statistically signifi-cant differences.11

Kaushal et al in their study on 60 subjects in a North Indian population found a statistically signifi-cant dimorphism in mandibular canines. The man-dibular left canine was seen to exhibit greater sexual dimorphism (8.8%) than the right mandibular canine (7.9%). They also concluded that if the width of the canine is greater than 7 mm, the probability of the sex of the person under consideration being male was 100%.1 Another study by Nair et al on South Indian subjects concluded that the left mandibular canine with 7.7%, followed by right mandibular ca-nine with 6.2%, shows the maximum sexual dimor-phism.12 The results of the present study, which was

Mean value of mesiodistal mandibular canine width (in mm)

Side Clinical Examination Plaster Models Radiographic Examina-

tion

P-value

Group Right 7.126 7.04 6.991 Males Left 7.173 7.133 7.04

Right 6.626 6.446 6.311 Females Left 6.533 6.46 6.36

<0.001

Figure 4. Comparison of sexual dimorphism on the right and left mandibular canines. 

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54 Kapila et al.

conducted on a South Indian Population, are consis-tent with the results of above-mentioned studies, where greater sexual dimorphism (9.7%) was exhib-ited in the left mandibular canine than in the right mandibular canine (7.4%) and when the width of the mandibular canine was greater than 7 mm, the prob-ability of the sex of the person under consideration being male was 90%.

Reverse dimorphism (where the females showed larger teeth than males) was found in studies carried out by Acharya and Mainali13 on mandibular second premolar in Nepalese population and by Yuen et al14 on mandibular incisors in a longitudinal study on Chinese population.

The present study establishes a statistically signifi-cant sexual dimorphism in mandibular canines. De-termination of sex by mesiodistal measurement of mandibular canines is a relatively quick, easy and inexpensive method, and can aid in identifying per-sons from fragmented jaws and dental remains.

It must be noted, however, that the method of sex determination via canine measurement has its limita-tions; the sex of the subject to whom the fragment of the mandible belongs can be determined satisfacto-rily only when the fragment is found in the geo-graphical area where the subject was born.

Conclusion

The emerging field of forensic odontology in India relies a lot on such inexpensive and easy means of identifying persons, and in such situations the dentist can be called upon to render expertise in forensic science. A database may be established of dental morphometric measurements using intraoral periapi-cal radiographs with a view to determine variations among large populations that may be beneficial for

anthropological, genetic, legal, and forensic applica-tions.

References 1. Kaushal S, Patnaik VVG, Agnihotri G. Mandibular canines

in sex determination. J Anat Soc India 2003; 52:119-24. 2. Dahberg AA. Dental traits as identification tools. Dent Prog

1963, 3:155-60. 3. Rai B, Anand SC. Gender determination by diagonal

distances of teeth. The Internet Journal of Biological Anthropology [serial on the Internet] 2007; 1(1):[about 7 pages]. Available from: http://www.ispub.com/ostia/index. php?xmlFilePath=journals/ijba/vol1n1/teeth.xml

4. Moss ML, Moss-Salentij L. Analysis of developmental proc-esses possibly related to human dental sexual dimorphism in permanent and deciduous canines. Am J Phys Anthropol 1997; 46:407-13.

5. Garn SM, Lewis AB. Bucco-Lingual size asymmetry and its developmental meaning. Angle Orthod 1967; 37:186-93.

6. Lysell L, Myrberg N. Mesio-distal tooth size in deciduous and permanent dentitions. Eur J Orthod 1982; 61:113-22.

7. Ateş M, Karaman F, Işcan MY, Erdem TL. Sexual differ-ences in Turkish dentition. Legal Medicine 2006; 8:288-92.

8. Karaman F. Diagonal measurements on teeth to predict gen-der in Turkish population. J Forensic Sci 2006; 51:630-5.

9. Hashim MA, Murshid ZA. Mesiodistal tooth width: A com-parison between Saudi males and females, Part 1. Egypt Dent J 1993; 39:343-6.

10. Hashim MA, Murshid ZA. Mesiodistal tooth width in a Saudi population sample comparing right and left side: Part 2. Egypt Dent J 1993; 39:347-50.

11. Al-Rifaiy MQ, Abdullah MA, Ashraf I, Khan N. Dimor-phism of mandibular and maxillary canine teeth in establish-ing sex identity. Saudi Dent J 1997; 9:17-20.

12. Nair P, Rao BB, Annigeri RG. A study of tooth size, sym-metry and sexual dimorphism. J Forensic Med Toxicol 1999; 16:10-3.

13. Acharya A, Mainali S. Univariate sex dimorphism in the Nepalese dentition and the use of discriminant functions in gender assessment. Forensic Sci Int 2007; 173:47-56.

14. Yuen KK, So LL, Tang EL. Mesiodistal crown diameters of the primary and permanent teeth in southern Chinese: A lon-gitudinal study. Eur J Orthod 1997; 19:721-31.

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